Concept:In permanent tree crop plantations, regular cutting of weeds with tools is the standard control method.Explanation:Tree crop plantations such as oil palm and cocoa are usually weeded by slashing weeds using a cutlass.Crop rotation is impractical because the land is occupied permanently by the trees.Hand pulling is too slow and costly for large plantation areas.Flooding is unsuitable for most tree crop plantations as it can damage the trees.Thus, slashing is the most widely practised and effective weed control method.Answer:D. slashing